Trigger mechanism for automatic firearms



April 17, 1952 F. MARcl-nslo 3,029,708

TRIGGER MECHANISM FOR AUTOMATIC FIREARMS I Filed Feb. 15, 1961 3Sheets-Sheet 1 "um: I'....".

April 17, 1962 F. MARCHISIO 3,029,708

TRIGGER-v MECHANISM FOR AUTOMATIC FIREARMS Filed Feb. 15, 1961 5Sheets-Sheet 2 April 17, 1962 F, MARCHlslo TRIGGER MECHANISM FRAUTOMATIC FIREARMS Filed Feb. l5, 1961 3 Sheets-Sheet 3 "llllllllillmnuuuum assess Patented Apr. i7, i962 United Se@ Parent Ot 3,029,703TRIGGER lit/H31(II-IANSIVI` FR AUTGMATEC 'i' .FIREARMS-v n FeliceMarchisio, 70ACorsoMassimo dAzeglio, Y 'i`nrin,ltaly m l Filed Feb.l5,f19;6iSer. No. 89,539 Claims priority, application Italy Feb. 22,196@ A2 Claims; (CL89-131).

This'invention relates to automatic firearms Suitable for selectiveaction of Asingle orcontinuous lire,of the type provided with a triggermechanism according to application iiled `in the U.S.A. Von the July'27,1960 Ser. No. 45,7ll.-"

This trigger mechanism comprises namely a reciprocating breech bolt, acasing arranged'beneath the breech bolt path,a -first and a second pivotAin said casing, a hammer capable of swinging-about said first mentionedpivot betweena recoil and a ring position over` a' path intersecting thebreech bolt path, so that recoil of the breech Abolt drives Y'the Yhammer i to its recoilk position,"spring-loaded means forming togetherwith the hammer a ltoggle link which moves the hammer to its first andsecond mentioned positions across a `deadmpoint position, a springloaded delay umass adjacent the hammer on said first mentioned pivotcapable of swinging about the latterl between a recoil and a :firingposition 'over -a'patli intersectinglthe breech bolt path, so thatrecoil of the breech bolt drives the delay mass `to its recoil position;vspring-loaded lock means holding the mass in itsrecoil position,4 a camsurface on the breech bolt actin-g on' said lockmeans for unlocking thedelay vmass on'return of the breech'bolt to its firing position, -alost`motion connection between `the delay mass and hammer adapted to movethe latter from its recoil position through its dead point position whenthe by Way of example, wherein:

`FIGURE l showsthe mechanism at the limit of the recoil phase of thehammer;

FIGURE 'shows the mechanism cocked, set for single shot action; i

'FGURE 3 shows the mechanism after a single shot has been fired, and vFIGURE =4 shows the mechanism set for continuous lire action; Y :FIGURE5 shows the mechanism set for increased rate FIGURE 6 shows anelevational view of an automatic tire arm provided with a triggermechanism according'to this invention.` v f The-trigger mechanism iscontained in a rectangular,

1 with -o'ne side plateremoved to `show theimecha'msm.

mass is near its firingposition; a Sear capable of swinging on saidsecond mentionedfpivot from a safety to a continuous firingposition'through a 4single tiring position and vice Versa, a toothprotruding `from thc'sear, a tooth radiallyprotruding from the harrnner,a two-arm beam, the arms of which-extend between the paths `ofthe saidtwo teeth, said beam being provided with -an eyelet extending in thedirection of theY ar-.ms cooperating with the second mentionedpivot,whereby the beam is moved by the tooth on the hammer acting on one ofits arms to'intersectby its other arm the path of the tooth on the scar,While holdingk the hammer inl its cocked condition, and spring meansacting onthe beam to displace the latter in the direction of said rstmentioned arm tocause said first mentioned arm to intersect the path ofthe tooth on the hammer, said tooth on the scar acting on the beam tomove the latter about said second mentioned pivot to move said rstmentioned arm out of range of the tooth on the hammer. 1 I

`A triggermechanism as described above shall be briefly referred tohereafter and in the appended claims as mechanism of the type specified.This mechanism afords-a substantially reduced continuous re rate,whereby thetcrm rate` is employedto designate the number of shots whichthe arm is capable of tiring in aminute under antomatictcontinuous)tiring conditions; -At reduced ,continuous tiring rate` can, however, beundesirable or disadvantageous under special emergency conditions. i r

`This invention provides a fire arm provided with a trigger mechanismvof the type specified whichaffords in continuonsziire; tworates ofiireatleast, one of which is substantially slower. i

Theinventionf therefore provides a trigger mechanism of the typespecified comprisingrnoreover manually controlled means acting betweenthe hammerl and delay mass Thelother side plate 1i supports three iixedpivotsiZ, i4 and i6 thatf extend toward-thefother side-plate. v

On pivot i2, ireelyi mounted side by side, are hammer i7 and vdelay mass18, :both having a form of a two-'arm lever. The arm 17a of the'hammeri7 andthe arm 18a of -the delay lmass u18 are provided intermediatelytheir llength with la through hole "itil and i632, respectively,bothholes having-axes parallel'to and eqnidistant from the-axis of thepivot 12. The arm 17a-of the hammer and thearin 'lafof the delay massnormally interfere with the' recoil path of the breech bolt Ztl, thesaid breech bolt contains a ring pin, its rearV part 2i protriidingfromthe rear of fthe breech bolt. l The arm Ha of hammer i7 moves-fin thissame planeas theiiringpin and by striking the extremity 2li of thelatter cause action. The arm 18a of fthedelay mass has a semicylindricalseat-'22 housing the'head 23a of a push rod 23. The tail part of thepiish rodslides in an opening 24 ofthe back plate 10a of casing l0.' Ahelical compression spring `25 is compressed on 'shank o-frod 23 betweenthe plate 10a and a collar on 'rod 232 so as to pnsh'the head`23a intorseat 22. The reciprocal arrangement of seat 22, pivot IZ'andopeningfZd- -f ensures that' the delay -mass i8 is continuously underaction of spring-25' (through rodf23) which' tends to- `swing-the delaymass towards the breech `bolt i.e. counterclockwise yon thev drawing. f

' The arm 17a of hammer -17 carries a pin 26, which engagesa fork 27a ofpush rod 27. The tail end of-this rod slides in Ian opening-in thebackplate lila, similarly as rodf23, anda helical compression spring 28 iscompressed on the shank'of rod27 between the plate lila and a col'-laren the rod, pushing the fork 27a against pin 26t Thereciprocalarrangement of pivot 12, pini zdand of the opening in thebackplate lila is in this case such as to` form a* toggle link Whereasthe hammer swings pin Z6 crosses'the' 'imaginary straight line joiningthe said opening with pivot l2. Thus, conditions being as shown in FIG.l, spring ZStends to swing the hammer 17 clockwise, while underconditions shown in FIGS. 2 to 4, hammer'17under`action of spring 28tends to swing counterclockwise.

The *other lever arm of hammer 17 carries a lateral iinger17bvprotruding into" the path of the delay mass 18. The delay mass 18.engages the lateral nger 17b by either an abutment siirface 30ysituated at the root of arm 13a or by another abutment surface 31 on theface of a tooth "18b which forms the vother lever yarm of the mass 18.Considering the conditions shown on FIG. l, the angular distance betweenfinger 17b and abutment surface 30 relatively to pivot 12, is such, thattowards the end of forward (counterclockwise) movement of delay mass 18towards situation shown on FIG. 2, the sur-face 30 meets finger 17b andtakes it across the dead centre, thus permitting the spring 28 to swingthe hammer towards the extremity 21 of tiring pin. The abutment surface31 of a tooth leb immediately adjacent to nger 17b as shown in FIG. 1,constitutes 'a stop for hammer 17 impeding any counterclockwisemovement. Hence, as a system, t-he parts 17b, 30 and 31 form a lostmotion connection between hammer and delay mass, the said connectionbecoming active in the end part of swing of the delay mass towardsbreech bolt 20, as described above.

With tooth 18b cooperates a pawl 32 fixed to a lever arm 33 pivoted onpivot 14, and controlled by a spring 34, which tends to bring pawl 32 onthe path of tooth 18b. As shown in FIG. l, where delay mass 18 andhammer 17 are both at their extreme clockwise swing, |the pawl engagesthe tooth 18h, thus locking the mass 18 against a counterclockwiseswing. Lever arm 33` coopcrates with Van unlocking lever 35 pivoted onpivot 12 `and projecting into the path of breech bolt 2i). rIhe latterhas a cam 36, which, immediately before the end of the locking stroke(to the left on the drawing) engages the lever 35 and swings itcounterclockwise. The cooperating surfaces of lever and arm 33 are such,that the above mentioned swing of lever 35 produces a counterclockwiseswing of arm 33 together with pawl 32, disenga-ging the latter fromtooth 18h, and thus unlocking the delay mass 18.

The trigger and sear 41 are pivoted on pivot 16. Wound around this pinis a spring 42, with one end bearing against pivot 12, the other endbearing against Itrigger 40, tending to keep the trigger in a neutralposition, as shown on FIGS. 1 and 2, where the trigger bears against -alimit stop 43, xed to casing 10. The rear part of the trigger 40 formsan arm 44, cooperating with a selector 45. The selector is lformed by apin able to rotate in supports in side plates of casing 10, and has adiametral incut 46. The selector is controlled by a wing (not shown) onthe out-side of casing and can be placed in three positionscorresponding to: safety, semiautomatic or single shot firing and fullautomatic or continuous tiring. These positions are depicted in FIGS. 1,2 and 4, respectively. The sear 41, T Kformed, is suspended on pin 16passing through an eyelet 47 parallel to the top bar of T; thissuspension permits oscillating and sliding motions of the sear. Theforearm 41a of sear 41 cooperates with a tooth 17C provided on hammer 17`for locking it in the cocked position, i.e. immediately after thehammer passed the dead centre checked by the surface 30 and finger 17b,as shown in FIG. 2.

The body of trigger 40 houses a plunger 50 (FIG. 2) pushed against thevertical bar of the T sear under action of a compression spring, thusthe sear 41 tends to slide forwards on the pin 16 and rotate suicientlyto bring its front arm 41a into the path of the hammer tooth 17e. Theplunger spring is weaker than the hammer spring 28, thus as shown inFIG. 2, the scar 41 is pushed backwards by the hammer tooth 17e. Inthese conditions, the rear arm 41b of sear 41 finds itself directlyabove a trigger tooth 51, and therefore the arm 41b is being raised-upwhen the trigger is pulled. Otherwise, when the sear is not engaged bythe hammer tooth 17C, and is brought forwards by plunger 50, the arm 41hdoes not engage with the trigger tooth 51 (FIG. l), under certainconditions, however, described later, the sear arm 41b can be en-gagedby a step 52 (FIGS. 3 and 4) adjacent to tooth 51.

Functioning of the above described mechanism is -as follows: as usualthe breech bolt is first pulled back by hand, to introduce a cartridgeinto the barrel. In this movement which does not differ from a recoilproduced by a shot, the breech is brought back as shown in FIG. l. Thedelay mass 18 and hammer 17 are swung completely back (clockwise in FIG.l); and the delay mass gets locked by pawl 32. Pin 26 of hammer togglelink falls below the dead centre, and therefore the hammer tends torotate clockwise under action of spring 28 and rod 27 and rests againsta suitable limit stop (not shown).

During the successive phase, when the breech bolt moves forward, cam 36engages unlocking lever 35, and by depressing it causes pawl 32 to freethe delay mass 18, which, under action of spring 25 and rod 23 swingscounterclockwise, until it is stopped against the rear face of breechbolt Z0. In the last path of its swing, the abutment surface 30 of the-delay mass 1S engages linger 17b of hammer 17 taking the latter acrossthe dead centre of toggle link. immediately the dead centre is passed,the hammer tooth 17C engages arm 41a of sear 41; the latter recedesovercoming action of plunger 50 and comes to rest in condition shown inFIG. 2. The plunger 50 and its spring act therefore as a shock absorberfor hammer 17. Now, the trigger mechanism being cocked, the furtheraction depends on the setting of the selector 45. FIG. 1 shows theselector in safety position, where the trigger larm 44 bears against thecylindrical part of the selector, thus locking the trigger. By turningthe selector clockwise by approx. 30 as shown in FIG. 2, a limitedcourse is given to the arm 44 which penetrates into selector cut 46. Itcan be seen from FIG. 2, that by pulling the trigger 40, tooth 51encounters the rear arm 41h of sear 41, and makes the said sear rotateon its pivot 16, until the hammer tooth 17C is set free land spring 28through rod 27 swings the hammer anticlockwise against the rearextremity of firing pin 21 `located in the breech bolt 20, causing ashot to be red.

Simultaneously, sear 41 slides forward under action of the spring loadedplunger 50, thus removing the rear arm 41]? from the path of tooth 5-1.After a shot has been tired, the breech bolt recoils, repeating allcocking motions as already described with reference to FIG. 1, the onlydifference being that if the shooter does not release the trigger, thesituation is as shown in FlG. 3. Consequently, Awhen the hammer tooth17e` strikes against the forearm 41a, moving backwards the scar 41, itsrear arm 41b slides on the step 52 and comes to rest against tooth 51(as shown in FIG. 3) locking the hammer 17.

This invention provides means for temporarily rendering ineffective saidlost motion connection.

According to @an embodiment of this invention said means comprises a pinreceived by said holes 101 and 102 bored both in the hammer f17 anddelay mass 18, the said holes being aligned along a common axis.

The holes move on swinging on both hammer and delay mass about the pivot12 over a slot 110 cut both through the side wall, `removed on thedrawing, of the casing 2t) and wall 111 which laterally confines thebody of the fire arm; the slot profile is an arc of a circle having itscenter on the axis of the pivot 12. The pin 10) can therefore beinserted into said holes from the outside through said slot from whichit protrudes over a suitable length.

Insertion of the pin 100 into said holes connects in rotation the hammerand delay mass, thereby annulling the delay with which the hammer movesfrom its recoil position to its tiring position, said delay beingotherwise determined by the time taken by the delay mass for moving fromits recoil position to its firing position.

Adoption of the pin 169- for rendering ineffective the labove mentionedlost motion connection further affords an increment in hammering actionby the hammer 17 on the striker carried by the breech bolt 20, thisincrement being due to the resultant action of both springs 25 and 28which then act simultaneously to move said hammer and delay mass fromrecoil to firing condition.

The concomitant yaction by the springs 25 and 28 affords full efficiencyof the irearm, even under unsatisfactory operating conditions 'such asare due to poor lubrication or dirt.

It will be understood that, the principle of the invention being leftunaltered, embodiments and constructional details may be Widely variedwith respect to the non limiting example described and shown withoutdeparting from the scope of this invention.

What I claim is:

l. In Aa tiring mechanism in an automatic rearm, a reciprocating breechbolt including a firing pin therein, a casing positioned below the pathof the breech bolt, a first and ra second pivot in the casing, a hammerswinga'ble on the first pivot between a recoil condition and strikingcondition on a path intersecting the path of the breech bolt whereby therecoil stroke ofthe breech bolt displaces the hammer towards recoilcondition of the latter, spring-loaded means jointly providing with thehammer =a toggle link causing the hammer to snap into its irst andsecond mentioned condition through a dead point condition, aspring-loaded delay mass swingable on the said rst pivot adjacent thehammer between a recoil condition and a firing condition on a pathintersecting the path of the breech bolt whereby the recoil stroke ofthe breech bolt displaces the delay mass to its recoil condition,spring-loaded lock means-locking the mass in its recoil condition, a camsurfaceon the breech bolt causing the said lock meanslto unlock the masson return of the breech to its firing condition thereby to canse thespring-loaded mass to swing into its tiring condition, a lost motionconnection between the delay mass and hammer eective on the hammer todisplace the latter from its recoil condition through its dead pointcondition as the mass is about to reach its tiring condition; a triggerswingable on the said second pivot from a safety condition to acontinuous tiring condition through a single shot condition andvice-versa, `a tooth projecting from the trigger, ia tooth radiallyprojecting from the hammer, a two-armed sear extending with its armsbetween the paths of the two teeth, the said sear having an eyelettherein elongated in the general direction of the arms accommodating`the said second pivot whereby the Sear is shiftableV by the tooth onthe hammer acting on one of itsvarms to intersect with its opposite arm,the path of the tooth on the trigger while retaining the hammer incocked condition, and spring means acting on lthe Sear to shift thelatter in the direction of the rst mentioned arm and cause the irstmentioned arm to intersect the path of the tooth on the hammer, the saidtooth on the trigger acting on the rear to swing the latter on the saidsecond pivot thereby to bring the rirst mentioned arm out of the path Noreferences cited.

